B4X Requires Chilkat v11.0.0+

Encrypt with Chilkat, Decrypt with OpenSSL

See more OpenSSL Examples

Demonstrates how to RSA encrypt a string using Chilkat, and then shows the corresponding OpenSSL command to RSA decrypt. The OpenSSL command to decrypt is as follows:

openssl rsautl -decrypt -inkey VP_Private.pem -in rsa_encrypted.bin -out original.txt

B4X

Dim success As Boolean = False

'  This example requires the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

Dim rsa As ChilkatRsa
rsa.Initialize

'  Note: RSA encryption uses the public key.  
'  RSA decryption uses the private key.
'  The reason is that the public key can be freely provided to anybody.  This allows anybody
'  to send an encrypted message to the private key owner, and only the private key owner 
'  can decrypt.
Dim key As ChilkatPublicKey
key.Initialize

'  Load an RSA public key from a PEM file:
success = key.LoadFromFile("qa_data/pem/VP_Public.pem")
If success = False Then
    Log(key.LastErrorText)
    Return
End If


'  Load the public key into the RSA object.
success = rsa.UsePublicKey(key)
If success = False Then
    Log(rsa.LastErrorText)
    Return
End If


Dim strToEncrypt As String = "00000000;XYZ2-3BHQ-ABCD-MMVV;6MY1-GHJK-9LRR;0"

'  The LittleEndian property is False by default, but it is set here
'  anyway to show that LittleEndian byte ordering is required for OpenSSL compatibility.
rsa.LittleEndian = False

Dim usePrivateKey As Boolean = False

encryptedBytes = rsa.EncryptString(strToEncrypt, usePrivateKey)
If rsa.LastMethodSuccess = False Then
    Log(rsa.LastErrorText)
    Return
End If


'  The OpenSSL command to decrypt would be this:
'  openssl rsautl -decrypt -inkey VP_Private.pem -in rsa_encrypted.bin -out original.txt

Dim fac As ChilkatFileAccess
fac.Initialize
success = fac.WriteEntireFile("qa_output/rsa_encrypted.bin", encryptedBytes)
If success = False Then
    Log(fac.LastErrorText)
    Return
End If


Log("RSA Encryption Succeeded.")